Nepal has two classic windows: October–November (stable skies, cold nights, busy tea houses) and March–April (blossom, a little haze). December–February is possible on lower Annapurna ridges; high passes get bitter. June–early September is monsoon. We run some short Pokhara walks then. We will not pretend the Circuit or ABC is a view week.
Rain-shadow Upper Mustang is the exception in those wet months.
For Annapurna-specific months see when to walk the Annapurna. Send dates; a manager in Pokhara answers the weather, not a calendar graphic.